Electrical plug and socket



Oct. 19, 1948. E. l.. scoTT 2,451,982

ELECTRICAL PLUG AND SOCKET Filed Jan. s1, 1945 l N VEN TOR.

A TTU/WYE YS Patented Oct. 19, 1948 sfr-Ares PATENT .'o-F-Pic--ELECTRICAL"PLUG`AND' SOCKET .Eben L:.-Scott, Mission, Kans.

*Apl'ilicationJanuarySL 1945, 'Serial No."575,391

"Ihis invention relates.l -to electrical connectors, particularly-plugand-"socket membersfonuse in connecting various -`.appliances or 'thelikefin anvelect'ric circuit andvhaslior itsprincipaloblject yto providea' r structure-y Wherein the livefconf' tacts are asubstantiallyinaccessible'.l through the plugl inlet :ofl'the--socketrmembenztherebyelimina-ting possibility Vof rshcrt `circuitsA .caused fbymetal objects ibeing' thrustinto .thef socket.

Further objects of the inventioniareitocpro--videea.connectorconstructed-:topreventl'accidenltal:ldisplacementioffthe plugw member by `pulling"or j erkingnon the:e1ectric cord connected'. thereto; .tolprovideiaeplug and `socket :construction :which maintainspostive electrical:contactvvhen the lplugLLzisninsertedzin@,the ksocket for assuring 1full :line zcurrentv tocan appliance.' served thereby.v and avoidingraros 'and rradio interferenceJ :ordinarily ,causedflby loose contacts;to provideva structure whereinxthwplug 'completely closes the socketopening :when:electrical contact :is :being-restab- .lishe`d; andf to:providefafconnec-torzfof relatively simple." and :inexpensiveconstruction.

lIn .l accomplishing theseandzzother lobjects -of the invention lashereinafter; pointed out, `I have provided improvedstructure, the4preferred.fo1m fof which isfillustratedfin. the'accompanying drawfingvwherein Fig- 1- is La? face View of :an electrical connectorconstructedi in accordance-with' the present .inven-tion.

.-rl'igiffZ isla -verticalusection throughthe con- Anector, part beingshown in ,elevationA -toillustrate connection .of :anelectrcal service-wire thereto.

fFig... 3 is a fragmentary cross section on .the .line ',3--3 ,of Fig.r1 particularlyillustratingthe manner-of closing access to thelivercontactswhen the ..plug member fis removedy .from the socketmember.

. Eigeds. a perspective view..of,the .pa1ftsfof* the socket member shownin'disassembled spaced relation to 'better illustrate the "constructionthereof.

Fig. 5 is a perspective viewof theplug member.

Figj 6-isa section througlroneof thel contacts ofV ltherplug Amembertakenhon the linefiIf-f'b` f -of *Figi 5.

""Fig "7 `is a* horizontalsectionthroughf the connector onfthe line'I-i'I v'of Fig.' 1'4 showing?. the'plug in position in the socket forestablishing anz'electric'al fconnection.

' Re'ferring more rinV detail' to the :drawings:

l" Ivdesignatesan 'electrical' connectorv embodying the features of thepresentixinvention-'zand l2 Claims. (CLN3-330) l2 which includes asockety member 2 'and' a plug member'3. The socketmemberZ"is/'preferably formed in two-sections fiend 5 `composedofinsulatingmaterial such asa plasticthat is "read- :ily formable to-desired shape. The fmember 5` includes a body`6 havingy onelor Vmorepreferably cylindrical recesses 'I openingl'fromaf'face side thereofbut-l terminating short fof fthefopposite f ace9 toprovide-'aninsulating lwall comjletelyfsurroun'ding :the lrecess.

`'Ihe connector 'illustrated vis ff'duplexf-type, fand, therefore, themember f 5 includes two'frecessesl located with their axes vin-parallelrelation andfspacedapartby a constrictedfportion as best shown in Fig.4. 'The outer contour-of they member 45 is preferably shaped`1.o..conforrn to the rec-essesand the-.sides .intermediatefthe recessesarecurVed inwardlylas rat` Illl to formt-the yportion@ `and-toa'ccommodate-terminalsv IIfzand :l2for` connectionfwith the leads1.I3".of:an-e1ec tric circuitas later described.

Thezsection -I constitutes :a ycover?iorltheisectionzand isofia sizelto,coverthefface side. 8 rof the'fsecticn and to .carry :theaterminals I I.zand I ZJSothatfthey. lieczad'ja'cent; the; curved 'faces I 0 and arecontained within the .limits fofzthe" section 5.

In .the illustrated instance'the cover-'d isisubstantiallyVrectangular-,and has suicient thicknessxbetween the frontand rearfaces'ILandl-IS .thereoilto thoroughlyainsulate'tcontact strips yI6 andI1 .andxprovide ample strength in resisting :pulling forces on any'electric :cord connected therewith through'a plug Emeniber`3. TheAconl :tact strips IIE5-and IIarefdisposed' on oppositesides'ofxpluginletropenings I8 .vhiclizregster` with the recessesll..The strips l i6 Aand'lly arewoffa -lengthLto intersectfrecesses I Sfand2i] .formed `in- .Wardly :fromlthe 'rear faces VI5*,andvvhichfare spacedfrom'athefopenings` `I 8 toV provide sulcient insulating :material f 2 If. therebetween for thoroughlyl insulating: the contact strips-randprevent .anyxcontact therewith exceptfrom the direction ofthefrear; faceI5-oi ,theicover member 4.' IIhe terminals IIzand` I2 are ipreferablyintegral 'with the xconta'ct 4strips and turned `laterally thererom''as:at'::22 to .project fromthe rearface I5 of; the lcoversection: azsuiicient distance to accommodatefscrewsrfor connectionof theservicezawires :Hbf: anfelectric circuit ,asl yindicated in Fig.V 2. Theopenings` I8; have central cylindrical portions.'2li.:locatedtcoaxiallywithy the; recesses.y 1 and J extending .therefromsare 'notch portions 25 and 26. offless-fwidthttl-lan the .diameters-.0f`the cylindrical portions The notches have relatively parallel sidefaces 21 joined with arcuate faces 28 formed on a radius correspondingto the radius of the recesses 1. The recesses I9 and 2U, while beingspaced from the inlet openings, are located within the limits of therecesses 1 as shown in Fig. 3.

It is thus obvious that the contact strips are exposed only through therecesses I9 and 20 and when the sections are connected together anyaccess to the contacts must be attained from within the recesses 1 andfrom the rear face of the cover section 4. The cover section 4 carriesears 29 at the ends thereof for attachment of the' socket member withina conventional boxinot.

shown).

The ears 29 lare preferably formed of metal and have yanchoring portions3U inset within recesses 3| provided 4on the rear face of the coversection 4 so that when the cover section is secured to the section y5the anchoring portions are clamped therebetween -as shown in Fig. 2.'I'he sections of the socket member are secured together by Ifasteningdevices such as screws 32 that extend through openings 33 in the coversection, registering openings 34 in the anchoring portions of the ears,land into threaded openings 35 formed in the section 5.

Contained within the recesses 1 are closures 36 for the plug 4inletopenings. The closures 36 are of disc-like form and of -a diameter to befreely movable axially of the recesses and to extend over the contactrecesses I9 and 20 through which the contact strips I6 and I1 areexposed. The front Ifaces 31 of the closures conform to the rear face I5of the front section 4' so that when engaged therewith there is no spaceoccurring about the margin of the plug inlet openings. The closures areyieldingly retained in closing position by coil springs 38 alsocontained With-in the socket recesses 1 and having one end bearingagainst the bottoms thereof and their opposite ends against lthe rearfaces of the closure discs, vas shown in Figs. 2 and 3, to urge thediscs in A-closing position yand to establish positive pressure on theplug 3 for assuring positive contact with the contact strips.

The plug 3 includes a substantially cylindrical body 39 of substantiallythe diameter of the cylindrical portion of the inlet openings and havinglaterally extending lugs 49 and 4I diametrical'ly arranged with respectto each other yas Vshown in Fig. 5. The lugs 40 and 4I have fiat sidefaces 42 (Fig. 5) to ypass between the faces 31 of the notch portions25-26 and arcuate end faces 43 to pass Ibetween the arcuate faces 28 ofthe notches so that Ithe plug is readily insertable through either oneof the inlet openings of the cover section when the lugs on the plug arealigned with the notch portions of one of the openings. The cylindricallbody portion of the plug has an axial bore 44 opening therethrough andwhich `intersects a transverse groove 45 provided in the rear face ofthe lugsas shown in Fig. 5. Formed in each lug and extending from thebottom of the recesses to the outer faces 46 of the lugs are openings 41(Fig. 6) mounting meta'l bushings 48 having internally threaded openings4'9 therein to mount contacts 50 having face portions 5I adapted toengage the exposed portions of the contact strips through the recessesI9 and 20. The faces 5I of the contacts are, therefore, spaced aslightly greater distance from' the front faces of the lugs than thedepth of therecesses as'sh-own in Fig. '1 so as to assure contact. The

threaded openings also mount screws I52 that have the shank portion 53inserted from lthe opposite ends of the bushings with the heads 54positioned within the transverse groove. The electrical cord 55 yispassed through the boss of the plug land the conductors therein areextended laterally through the groove to be anchored by the screws 52`to the contacts.

In assembling a socket member constructed as described, the springs 38yare inserted in the recesses 1 of the section 5 followed :by theclosure :plates 36. 'The ears 29 Iare then applied to the ends of thecover section 4 so that the anchor portions 30 thereof lie within therecesses 3|. The cover section 4 is then applied over the face side ofthe section 5 with the terminals I I and I2 passing over the sides ofthe section `5. The screws 32 are then inserted to complete the assemblyof the socket element. The leads I3 form an electric circuitand areconnected by the screws 23 with the terminals II and I2 and the socketelement is pushed into the box for lattachment therein as inconventional manner. 'Ihe box is then preferably covered by anornamental cover plate 56 of conventional design except that the plugopenings 51 thereof conform in shape to the inlet openings of the coversection 4. The cover plate 56 is secured in position by a fasteningdevice 58 extending through an opening thereof and engageable in athreaded -opening 59 in the cover section.

In using the connection, the plug 3 is inserted into one of the openingsI8 by holding it in position so that the lugs 4I and 42 thereon registerwith the notch portions 25 and 26 of the opening. When in registeringposition, the plug is pushed through the opening so that it bears uponthe closure disc 36 and additional pressure on the plug moves the disc36 away from seating Contact with the rear face I5 of the cover section4. When the contacts have cleared the cover section the plug is rotatedto bring the lugs thereon in registry with the recesses I9 and 20. Then,upon releasing pressure, the stored up tension in thecoil spring 38presses the disc 36 against the plug and effects suicient outwardmovement thereof for the contacts to enter the recesses I9 and 29 andengage the contact strips I6 and I1 thereby making a positive electricalconnection with the electric circuit to which the connector is attached.When thus engaged, it is impossible to remove the plug without exertingsufficient pressure in opposition to the spring 38 for moving thecontacts out of the recesses I9 and 20. Even then, it is necessary torotate the plug to bring the lugs thereon into registry with the notchportions 25 and 26 of the inlet openings before the plug can be removed.As the plug is removed, the spring urges the closure disc in followingcontact with the end of the plug so that by the time the plug completelycloses the inlet opening and is being withdrawn therethrough, theclosure plate seats against thev inner face of the cover section andthis is before the plug has been removed from closing relation with theopening. From the foregoing itis obvious that I have provided anelectrical connector of simple and relatively inexpensive constructionthat is safe and dependable and which cannot be short circuited byobjects accidentally inserted into the socket.

It is also obvious that when the connection is made the plug membercannot be accidentally removed by pulling or jerking upon the cordconnected therewith.

What I claim and desire to secure by Letters Patent is:

1. In a device of the character described, a socket element having arecess therein, insulating means covering said recess and provided witha plug inlet opening including a circular portion substantially coaxialWith the socket and substantially oppositely arranged radial notch-likeportions, said insulating means having seating faces at the sides of thecircular portion and facing said recess and having contact exposingrecesses within and completely surrounded by said seating faces, contactelements within said insulating means and exposed through said recessesin the seating faces, a closure member in said socket-like recess andhaving marginal portions contacting the face portions completely aroundthe contact exposing recesses to completely cover the exposed portionsof the contacts, and a coil spring in the socket recess and bearingsubstantially circumferentially of said marginal portions for urging theclosure member into contact with said seating faces.

2. In a device of the character described, a socket element having arecess therein, insulating means covering said recess and provided witha plug inlet opening including a circular portion substantially coaxialwith the socket and radial notch-like portions, said insulating meanshaving seating faces at the sides of the circular portion and facingsaid recess and having Contact eX- posing recesses within and surroundedby said seating faces, contact elements Within said insulating means andexposed through said recesses in the seating faces, a closure member insaid socket-like recess and having marginal portions contacting the faceportions completely around the contact exposing recesses to completelycover the exposed portions of the contacts, a coil spring in the socketrecess and bearing substantially circumferentially of said marginalportions for urging the closure member into contact with said seatingfaces, and a plug member having a head conforming to said circularportion of the plug -inlet opening and having radially directed lugportions adapted to pass through the notch-like portions When theclosure member is depressed against action of the spring and havingcontact elements for substantially lling said contact exposing recesses,said lugs having marginal portions surrounding the contact elements toclose said contact exposing recesses when the plug member is in positionin the socket element.

EBEN L, SCOTT.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,509,889 Kuhn Sept. 30, 19242,102,625 Hubbell Dec. 21, 1937 2,230,658 Stull Feb. 4, 1941 2,312,017Ackerman Feb. 23, 1943 FOREIGN PATENTS Number Country Date 27,585 GreatBritain (1903) Feb. 25, 1904

